LetterAgent
Mail physical letters by just asking your AI assistant.
Home > Guides > When to double-box a package
Double-box anything fragile, high-value, or oddly shaped: electronics, glass, ceramics, instruments, and items with protruding parts. The method is an inner box packed snug around the item, cushioned inside a larger outer box with at least two inches of padding on every side. Ordinary sturdy items like clothes or books in a good box usually do not need it.
Two boxes protect against two different failures. The inner box keeps the item from moving, which is what breaks fragile goods: damage comes from impact and shifting, not from the cardboard being thin. The outer box takes the punishment from stacking, drops, and conveyor belts, and the cushioning gap between the boxes absorbs the shock before it reaches the inner box. A single box, however strong, couples the item directly to whatever the box hits. Two boxes with a cushioning gap decouple them.
This is also why double-boxing is the standard advice from carrier packaging guides: it works for items the carrier's default handling would otherwise destroy. Sorting equipment drops parcels from heights onto steel; a cushioning gap turns a hard drop into a soft one.
Pack the item into the inner box so it cannot move: wrap it in bubble wrap or foam, fill every gap, and shake-test the closed box. If you hear movement, add more fill. Then choose an outer box at least four inches larger in each dimension (that gives you the two-inch gap on every side). Set the inner box in the middle on a bed of packing peanuts, foam, or crumpled kraft paper, fill around all six sides, and tape every seam of the outer box with the H-taping method: one strip down the center seam plus one along each edge.
The mistake people make is using an outer box that is barely larger, which leaves a half-inch gap that compresses on the first drop and behaves like a single box. The gap is doing the work; skimping on it wastes both boxes.
| Item type | Double-box? | Notes |
|---|---|---|
| Ceramics, glass, mirrors | Yes | The classic double-box case |
| Electronics, hard drives, screens | Yes | Impact kills components; also consider anti-static wrap |
| Instruments (violins, brass) | Yes | Hard case counts as the inner box; add the outer box around it |
| Clothes, books, soft goods | No | One good box with sensible fill is enough |
| Durable small parts, metal tools | Usually no | Padding against each other matters more than a second box |
It can, because the outer box is bigger and heavier than a single box. Carriers charge on whichever is greater, the actual weight or the dimensional (volumetric) weight, so a much larger outer box can push the parcel into a higher price bracket. Do not shrink the outer box to dodge this: a gap that is too small defeats the protection. Pack correctly first, then weigh and measure the finished outer box and buy the label for those final dimensions. If you get a shipping label from LetterAgent, the quote is based on the parcel you describe, so describe the double-boxed finished size.
Ready to ship it? Get a shipping label with LetterAgent: describe it to your AI assistant, approve the exact quoted price, and get your label.
LetterAgent is a working name. Prices include print, postage, and our service fee. US prices in USD, Canadian prices in CAD (Canadian prices exclude applicable sales tax, added at checkout). Currently in private testing.
Need help? Ask your assistant: it can check a job's status any time. If it ever can't handle something: hello@getletteragent.com